1. Technical Field
The present invention relates to a sensor element, a sensor device, and an electronic apparatus.
2. Related Art
Sensor elements that detect physical quantities such as angular velocities and acceleration are used for vehicle body control in vehicles, self-location detection of car navigation systems, vibration control correction of digital cameras, video cameras, etc. (so-called camera shake correction), for example. As an example of the sensor element, for example, a vibration gyro sensor (angular velocity sensor element) has been known (for example, see Patent Document 1 (JP-A-2009-156832)).
For example, the angular velocity sensor element disclosed in the patent document has a transmission arm (base part) fixed at both ends, four drive arms (drive vibrating arms) and two detection arms (detection vibrating arms) extending from the transmission arm, and pairs of piezoelectric elements each provided to each drive arm and each detection arm. Regarding the four drive arms, the two drive arms extend from one end part of the transmission arm in opposite directions, the other two drive arms extend from the other end parts of the transmission arm in opposite directions. Further, the two detection arms extend from the center part of the transmission arm in opposite directions.
In the angular velocity sensor element disclosed in Patent Document 1, by alternately repeating movements of expanding one piezoelectric element of the pair of piezoelectric elements of the drive arm and contracting the other piezoelectric element, the drive arm is flexurally vibrated (driven) to perform the so-called in-plane vibration. Further, when a predetermined angular velocity is applied in the drive state, flexural vibrations (in-plane vibrations) of the transmission arm and the detection arms are excited by Coriolis force, and electric charge is output from the pairs of piezoelectric elements of the detection arms. By detecting the electric charge, the angular velocity may be detected.
In related art, in the angular velocity sensor element, the pairs of piezoelectric elements provided on the detection arms have shapes simply and linearly extending in the extension directions of the detection arms, and thus, there has been a problem that it is impossible to efficiently detect the in-plane vibrations of the detection arms or sufficiently improve detection sensitivity.